Process of forming laminated products



Patented A r. 13, 1943 PROCESS OF FORMING LAMINATED PRODUCTS Oswald C. H. Sturken, Closter, N. J., assignor to Corn Products Refining Company, New York, N. Y., a corporation of New Jersey No Drawing. Original application June 23, 1938,

Divided and this application May 22, 1939, Serial No. 275,057

Serial N 0. 215,407.

4 Claims.

This invention relates to the production of laminated articles, bodies or structures composed of sheets of paper or other fibrous material united, usually by pressure, through the agency of a suitable adhesive binder forming unitary structures in which the identity of the individual sheets may or may not be completely obliterated; and the primary object of the invention is to provide articles of this character, the adhesive binder of which consists essentially of zein, the alcohol soluble portion of corn (maize) protein, and which articles shall contain a substance or substances of the bitumen-wax type; the paper sheets of which articles may, for example, be

coated or impregnated with such substance, whereby the articles will be tough, strong and highly water resistant.

A further object of the invention is to provide certain novel processes for the production of laminated structures'or articlesoi the character indicated. These processes involve certain procedures whereby the zein is put into colloidal solvents appropriate to each and their solutions mixed together. These substances also reduce brittleness and with such function in view may be regarded as plasticizers.

In the hot process the plastifying or plasticizing agent consists of one or more of a group of substances capable of converting the zein into a state in which it will flow and mix with the dispersion in the bitumen-wax substancei gr.

substances.

The term substances of the bitumen-wax type, or substances of the group consisting of the bituminous and waxes," or equivalent terms, as used herein, are intended to include the bitumens consisting chiefly of saturated hydrocarbons such as the asphalts, either'native or the residues, of petroleum and coal tar distillations;

the mineral waxes, consisting mainly of satu-.

- rated hydrocarbons and free oxygen bodies such as ozokerite, ceresin, montan wax and parafiin; the unsaturated hydrocarbon 'bitumens such as the tars derived from the destructive distillation of wood, coal and other organic material; the pitches derived from the destructive distillation of wood, coal, or animal or vegetable oils (see Standards of 1936 published bythe American Society for Testing Materials, page 1116); the animal waxes, such as beeswax and spermaceti; and the vegetable waxes, such as carnauba, candellila and pisang waxes.

The invention contemplates two different processes, giving in the end substantially simil: articles, both characterized by the colloidal dispersion of the zein in the bitumen-wax substance: one a hot process, in which a plastifying agent is used to put the zein in a flowing state so that, under the influence of heat and pressure, the desired homogeneous mixture or blending of the zein and bitumen-wax substance will take place; and the other a cold process, in whlch the zein and bitumen-wax substance are dissolved by molten bitumen-wax substance. The plasticizing substances which have given the best results are di-butyl tartrate, glycol phthalate, di-ethylene glycol and tri-ethylene glycol. Preferably a volatile solvent for the zein, such as ethyl alcohol of (volume) concentration is used in addition to the plastifying substance.

In the cold process each substance, that is, the

zein and the bitumen-wax substance, is dissolved in a solvent appropriate for such substance and the solutions are mixed together. The usual and preferred solvents for the zein are the alcohols, particularly aqueous, ethyl alcohol, although aqueous methyl or propyl alcohol might be used, The solvent for the bitumen-wax substance will depend upon the particular bitumen-wax substance dealt with. In any case, the solvent must be compatible with the zein and be one that will .not cause the zein to precipitate or the mixture of zein and bitumen-wax substance to stratify. Suitable solvents for asphalts or other bitumens are toluol and carbon tetrachloride; ior carnauba wax", ethyl alcohol; forcandellila wax, carbon tetrachloride; for pisang wax, anrvl alcohol or turpentine.

To enhance toughness and strength a curing agent, such as formaldehyde, may be utilized, either as an ingredient of the mixture or for the subsequent treatment of the articles after the blending of the zein with the bitumen-wax substance has been effected.

. Ordinarily the methods of procedure above referred to and more particularly described in the examples to be given below involve dipping the paper or other sheets, which have been previously impregnated with the bitumen-wax substance, into the fluent zein compound, made fluzein dispersed therein may be effected in one operation instead of two.

I in a stack, are placed in a press, and while being heated to a temperature between 200 F. (93 C.) and 275 F. (135 C.) are subjected to a pressure of 1500 pounds per square inch for, from one to ten minutes. By. this method the previously melted zein blends with the bitumen wax substance, which is melted by the heat of the press, and the sheets are made to adhere together very firmly to form a unifid body which is tough and water resistant.

EXAMPLE 2.--Hot process.In this process a zein solvent is used with the plasticizer to'bring about better dispersion of the zein in the bitumenwax substance. The formula for the zein solution is, in parts by weight, as follows:

Parts Zein 100 Di-butyl tartrate -i 22 Ethyl alcohol of 92% (volume) concentration 240 Water 30 The paper sheets, impregnated with the bitumen-wax substance, are dipped into the zein solution, taken out and dried at a temperature of about 175 F. (80 C.) until all of the alcohol is removed, and are then treated as described in Example 1 to melt the zein and blend it with the bitumen-wax substance. The ethyl alcohol concentration may vary from 70% to 95%.

EXAMPLE 3.Hot process.-The formula is the same as in Example 2 except that to give added strength and toughness to the article formaldehyde, preferably in the form of formalin, a 40% water solution of formaldehyde, is added to the zein solution in quantity to give 3%-10% of free formaldehyde based upon the weight of the zein. The process of forming the laminated articles may be the same as in the previous example.

EXAMPLE 4.Clcl process.-The zein solution is composed of the following substances in proportions by weight as follows:

Parts Zein 100 Ethyl alcohol 95% concentration. 160 Water 20 Toluol 87 the wax solvent used is carbon tetrachloride.

The mixture is heated until the materials Exmts 6.-C0lcl procesa-The bitumen-wax substance here is Pisang wax and the preferred solvent is amyl alcohol.

EXAMPLE 7.--Cold process.-Here the bitumenwax substance is carnauba wax, and the preferred, solvent is ethyl alcohol, the same solvent ,used for dissolving the zein.

By referring to the laminated articles of this invention as composed of sheets of material impregnated with a composition consisting essentially of zein and a substance of the bitumenwax type, it is not intended to exclude plasticizers other than those named, fillers, or other materias which for special purposes may be incorporated into the article.

This is a division of pending application Serial No. 215,407,flled June 23, 1938.

I claim:

1. Process of making a water resistant laminated article which comprises: dipping sheets of fibrous material impregnated with a substance selected from the group of substances consisting of the bitumens and waxes into a cold solution of zein, a zein solvent and a solvent of the bitu men-wax substance which is compatible with zein; and uniting the impregnated sheets by presmixture containing zein, a zein solvent and a 501- 1 vent of the asphalt which is compatible with the zein to form an adhesive and water resistant bonding medium; and uniting the sheets, in superposition, by pressure.

4. Process of forming a laminated article from :asphalt impregnated sheets which comprises:

bringing into con-tact with the asphalt a solution .mixture containing zein, an alcoholic solvent of zein, and toluol to form a water resistant adhesive bonding medium; and uniting the sheets, in

super-position, by pressure.

OSWALD C. H. STURKEN. 

